What is the difference between quantum chips and quantum dot technology?

The latest quantum chip "Willow" launched by Google was officially announced on December 9, 2024. The announcement was announced via Google's official blog and quickly attracted widespread attention from the tech community and media. The Willow chip demonstrates significant technological advancements, notably a breakthrough in quantum error correction, being able to complete a standard benchmark calculation in less than five minutes, compared to the same task performed by today's fastest supercomputers. To implement it, it will take about 10^25 years. This marks an important milestone in the field of quantum computing.

But for us, what affects us most about quantum technology is the screen with quantum dot technology.

Quantum dots are different from quantum chips, but have basic principles based on quantum mechanics. Both technologies exploit the unique properties of nanoscale materials to achieve extraordinary things that cannot be achieved with traditional systems. Recent advances in quantum chip development prompt us to consider how advances in one area can inform or inspire innovation in another.

In this article, we’ll take a closer look at quantum chip and quantum dot technologies to gain a complete understanding of how they work and their impact. By exploring the interaction between quantum chips and quantum dots, we can have a simple understanding of these two technologies.

I. Quantum Chips: A Path to Supercomputing

A quantum chip is the core component of a quantum computer, utilizing qubits for information processing. Unlike binary bits in classical computers, qubits can exist simultaneously in states 0 and 1, known as "superposition." Additionally, qubits can form a special connection called "entanglement," which allows quantum computers to excel at solving certain complex problems far beyond classical computers' capabilities. For instance, the photonic quantum computer "Jiuzhang" developed by Pan Jianwei’s team at the University of Science and Technology of China achieved speeds one hundred trillion times faster than the fastest supercomputer in Gaussian boson sampling tasks. This means that a task requiring one hundred million years on a supercomputer could be completed in about 200 seconds by "Jiuzhang," marking a significant breakthrough in China’s quantum computing research.

Google’s 53-qubit processor "Sycamore" also demonstrated quantum supremacy by completing a task in 200 seconds that would take a classical computer approximately ten thousand years. Google used random circuit sampling to generate an extremely complex output distribution that was difficult for classical computers to simulate, setting a milestone in quantum computing. In practical applications, D-Wave Systems has applied its quantum annealing machines in various industries, such as automotive manufacturing and financial risk assessment, providing new pathways to solve complex optimization problems. For example, Volkswagen Group collaborated with D-Wave to optimize traffic flow management, while Fidelity Investments leveraged D-Wave’s quantum computer to enhance trading strategy analysis. These examples show how quantum computing is already transforming industry operations even in its early stages.

Although quantum computers exhibit impressive potential, they are not suitable for all types of computational tasks. Their advantages mainly lie in problems that can be accelerated through efficient quantum algorithms, like factorization and molecular structure simulation. For simple arithmetic operations, quantum computers offer no significant benefits over classical ones. Therefore, we should consider why quantum computers outperform classical ones in certain areas? Does this superiority mean we should abandon research and development of classical computers? In reality, both have their strengths, and the future computing environment will likely involve complementary use of quantum and classical computers. We can envision that highly complex computing tasks will be handled by quantum computers, while everyday basic computations will remain dependent on classical devices. This not only improves efficiency but also promotes effective resource allocation.

II. Quantum Dots: Nanoscale Sources of Multicolored Light

Quantum dots are nanoscale particles composed of II-VI or III-V elements, typically ranging from 2 to 10 nanometers in diameter. Due to their small size effect, quantum dots exhibit unique photoelectric properties, emitting different wavelengths of light based on their size, producing colors from blue to red. Researchers at MIT developed an efficient solar cell based on perovskite quantum dots, achieving a conversion efficiency of 23%, significantly higher than traditional silicon-based solar cells. This study shows that fine-tuning the size and composition of quantum dots can substantially increase the energy conversion efficiency of solar cells, offering new solutions for clean energy.

Quantum dots possess extremely high luminescence efficiency, especially in visible and ultraviolet light bands, with quantum yields reaching up to 90%. Samsung Electronics’ QLED TVs use quantum dot enhancement films to significantly improve color performance, making screen displays more vivid. In medical imaging, fluorescently labeled quantum dots enable scientists to observe cellular structures more clearly. The Fraunhofer Institute in Germany made progress in quantum dot lighting technology, developing LED bulbs that are more energy-efficient and longer-lasting. Traditional incandescent and fluorescent lamps have issues with high power consumption and short lifespans, whereas quantum dot LEDs stand out with their high efficiency and longevity, promoting the development of green lighting industries.

Quantum dots are not limited to optical applications; they can also serve as fundamental units in building quantum computers. For example, semiconductor quantum dots can encode qubits and manipulate single qubits via microwave pulses or purely electrical methods. Certain types of quantum dots, like spin qubits based on SiGe heterojunctions, lack nuclear spins, resulting in longer quantum decoherence times, making them ideal for multi-qubit coupling. As quantum dot technology advances, future displays may become brighter and more realistic, and solar cell efficiency will increase, helping to alleviate energy crises. However, this also presents environmental and cost challenges, requiring us to think about balancing technological innovation with sustainable development.

III. Differences and Connections Between the Two

Quantum chips and quantum dots, though both rooted in quantum science, focus on distinct technical directions and service objects. Quantum chips aim for superior computational power, while quantum dots leverage their unique physical properties across various industrial and technological fields. Together, they constitute essential parts of modern science and technology, showcasing humanity's exploration of the microscopic world. For example, researchers from Hefei University of Technology and the University of Science and Technology of China successfully applied graphitic carbon nitride to next-generation quantum dot display technology, preparing novel quantum dot display devices. This achievement improved screen brightness and contrast, reduced energy consumption, and extended lifespan, heralding a new revolution in display technology.

Given that quantum dots can play a role in quantum computing, how should we view the relationship between quantum dot technology and quantum chips? Is there a possibility of integration that could promote mutual growth? For instance, future quantum computers might combine the advantages of quantum dots to create more stable and efficient qubits. Such speculation broadens the application scenarios of quantum technology and provides new avenues for scientific research.

IV. Conclusion

Although both quantum chips and quantum dots are based on quantum mechanics, they differ significantly in practical applications and development directions. Quantum chips aim to build next-generation supercomputers, while quantum dots serve various daily life applications. As research deepens and technology develops, we anticipate these technologies will bring unexpected changes to our lives in the near future. Whether improving medical diagnostics or advancing new energy technologies, the power of quantum science is quietly transforming the world.

How should we prepare for the social changes brought by these new technologies?